This invention relates generally to devices for connecting electrical cords for electrical tools and appliances, and more particularly, relates to apparatus and methods for maintaining secure connection of a first electrical cord and plug to another cord and plug.
In many industrial and commercial environments, it is often useful or necessary to connect a number of electrical extension cords, or to connect an extension cord to an electrical appliance. In these environments, if the plug and socket combination inadvertently disengage during use, such disconnection can cause inconvenience, down time, and even potential safety hazard.
Accordingly, various devices have been proposed and developed for retaining an electrical cord and plug to another cord and plug. Examples of such devices are set forth in the following U.S. Patents:
______________________________________ Patent No. Inventor ______________________________________ 3,475,716 Laig 3,613,046 Kirk 4,097,105 Zumwalt 4,440,465 Elliott et al. 4,690,476 Morgenrath 4,702,540 Siemon 4,917,626 Barton 4,957,450 Pioszak 5,026,300 Varner 5,044,976 Thompson 5,104,335 Conley et al. ______________________________________
By way of example, U.S. Pat. No. 4,690,476 to Morgenrath is directed to a device in which extension cords are secured together by first and second flexible strap elements, one having rings secured to its free ends, the other having mating hook and loop fastener elements attached to its free ends. When assembled, the second strap element is threaded through the rings on the first strap element and folded such that the hook and loop elements engage to secure the straps. U.S. Pat. No. 4,917,626 to Barton discloses a hook-and-loop securement system in which a strap having hook material is adhered to either side of a power tool plug such that the straps extend past the face of the plug for a selected distance. A pad of loop material is adhered to either side of the extension cord socket to engage the hook material when the plug and socket are engaged.
U.S. Pat. No. 4,957,450 to Pioszak is directed to a retainer assembly for releasably securing an electrical power plug and socket in a connected state to avoid inadvertent disconnection. The retainer includes a strap attached to the plug and socket, respectively, with securing elements for releasably attaching the opposite ends of the strap together to retain the plug and socket in the connected state.
U.S. Pat. No. 5,026,300 to Varner is directed to a plug-to-outlet retaining system utilizing cooperating hook and pile elements on the plug and the receptacle face.
U.S. Pat. No. 5,044,976 to Thompson discloses a plug-to-outlet retention system utilizing hook-and-loop fasteners, in which a cord-engaging element is fastened to a bracket affixed to the outlet.
Cord- and plug-securing devices typical of the prior art, however, suffer from a number of deficiencies. For example, conventional plug retention devices generally do not provide a high strength connection resistant to tensile forces. In particular, as the retention elements stretch under tensile loads, the plug and socket combination may inadvertently disengage during use, causing inconvenience and possibly a safety hazard.
Moreover, when employed in work sites and other areas in which dust and debris are prevalent, the hook and loop fastening strips utilized in certain conventional plug retention devices can become clogged with accumulated dust, thereby reducing effectiveness. In particular, as the individual hook and loop fastening elements fill with dust, the pull strength of the hook/loop connection decreases, such that the plug can pull away from the socket. Further, many conventional plug retention devices have little adjustability to various sizes of plugs and cords, so that they can not be utilized to accommodate larger high-amperage cords and plugs.
It is accordingly an object of the invention to provide improved plug retention methods and apparatus. Another object of the invention is to provide such apparatus that securely maintain engagement between plug and socket.
It is a further object to provide such apparatus that maintains a high strength connection between plug and socket in all types of environments. Yet another object of the invention is to provide such apparatus that can accommodate various sizes and configurations of electrical plugs, cords, and sockets.
Other general and specific objects of the invention will in part be obvious and will in part appear hereinafter.